Rock-cutting tool



Dec. 27, 1927. 1,653,663

0. ROLFSEN ROCK CUTTING TOOL Filed July 12, 1922 dwmirw 01., fiL-efv- GM, ADM-6, M

Patented Dec. 27, 1927.

UNITED STATES 1,653,663 PATENT OFFICE.

OLE noLFsnN, or LARVIK, NORWAY.

ROCK-CUTTING TOOL.

Application filed July 12, 1922, Serial No. 574,425, and in Norway July 23, 1921.

The present invention relates to rotary rock cutting tools and has for its object to provide a mechanically operated rock cutting tool of simple and cheap construction.

which may serve equally well for treating plane surfaces of rock as for the purpose of boring tunnels and breaking up stones.

According to the invention the rock cutting tool comprises a head of a heavy hard material such as hardened steel, said head being connected by means of a link with a rapidly rotating hub or spider.

Preferably the hammer head may begiven a substantially triangular shape and may be mounted with a certain amount of loose play on the free exterior end of a link, the inner end of which is again mounted with a certain amount of loose play in a hub or in the free end of a spider arm fastened on a rotating' hub.

Further the invention relates to the construction of the hammer head, and the connection of the latter with the loose link as well as the connection of the loose link with r the rotating hub or spider.

()n the drawing:

Fig. 1 is a side view of the hammer and arm with one of the links removed and Fig. 2 is a section on the line IIII of Fig. 1.

The hammer 1 has a substantially triangular shape and is mounted on trunnion 2, which connects the free ends of two links 3. Trunnion 2, as will be seen on the drawing, is provided with an excentric er;- pansion between the links 3 in order to obtain a large bearing surface between hammer 1 and trunnion 2, and at the same time keeping the exterior ends of links 3 a certain distance back from the working surface of hammer head 1.-

The boring 4 in the hammer head serving to take up trunnion 2 is somewhat larger than. the expanded part of the trunnion 2 passing through the said boringand has approximately the same triangular shape as the circumference of the hammer head, the corners being heavy curved so as to fit the circumference of trunnion 2.

The inner ends of links 3 are connected with an arm 5 by means of a trunnion 6, which is provided with an excentric expansion in the same manner as trunnion 2 in order to provide a larger bearing surface 55 between arm and trunnion. Arm 5 is integral with a hub 7 mounted on a rotating shaft 8. Said shaft may be provided with two or more similar arms 5 each carrying one cutting hammer. 7

hen arm 5 rotates in the direction indicated by the arrow, the tool is brought to engage rock surface 9, hammer 1 will strike the rock surface with the corner, which is foremost in the direction of movement. Thereby the hammer head is rotated with regard to the trunnion 2 and comes to rest with regard to the trunnion with the next corner of the triangular boring in engagement with the trunnion. 7

During the rotation of the hammer head the striking edge of the same slips away from the rock surface and after the comple tion of one rotation the rock is struck with the next striking edge.

Owing to the loose play provided in the connection between hammer head and links as well as between links and arm all jamming effect between hammer head and rock surface is prevented, and owing to the continual rotation the hammer head caused by each stroke against the rock a uniform bore of the striking edges is obtained.

In order to minimize the friction between trunnion 6 and arm 5 it is obvious that a ball or roller bearing may be substituted for the simple bearing illustrated at this point. This however need not be further described or illustrated as it is an ordinary feature of construction and does not constitute any part of the invention.

Claims:

1. In a rock cutting tool, a rotating shaft and hub thereon, radial arms on said hub, links pivoted with loose motion at the free end of said arms, hammer heads rotatably mounted with loose play on pivots at the free ends of said links, and the distance between the pivots being such that the hammer heads can perform complete rovolutions at all times.

2. Tn a rock cutting tool, a rotating shaft and. hub thereon, radial arms on said hub, twin links pivotally and loosely connected with their inner ends to the free ends of said arm, a trunnion connecting the free ends of said free links and a hammer head provided with a number of rock cutting edges loosely mounted on said trunnion between the free ends of the links, and the distance between the trunnion and the pivot being suflicient to permit the hammer head to perform complete revolutions at all times.

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3. Ina rock cutting tool, a rota-tingshaft and hub thereon, radial arms on said hub, twin links pivotally and loosely'eonnected with their inner ends to the free ends of said arms, a trunnion connecting the free ends of said free links, said trunnion being provided with an excentric cylindrical enlargement between the links, a hammer head loosely mounted on said excentric enlargement and the distance between the trunnion and the pivot being sufficient so that the hammer head is permitted to perform complete revolutions at all times.

4. In a rock cutting tooha rotating shaft and hub thereon, radial arms on said hub, twin links pivotally and loosely connected with their inner ends to the freeends of said arms, a trunnion connecting the free ends 01 said tree links, said trunnion being provided with an excentric cylindrical enlargement between the links, a polygonal hammer head loosely mounted on said excentric enlargement and the distance between the trunnion and the pivot being such that the han'imer head is permitted to perform complete revolutions at all times.

5. In a rock cutting tool, a rotating shaft and hub thereon, radial arms on said hub, twin links pivotally and loosely connected with their inner ends to the free ends of said arms, atrunnion connecting the free ends of said 't'ree links, said trunnion being provided with an excentric cylindrical enlargement between the links, a triangular ha miner head loosely mounted on said excentric ei'ilargement and the distance between the trunnion and the pivot being such that the hannner head is permitted to perform ronnilete revolutions at all times.

(3. In a rock cutting tool, a rotating shaft and hub thereon, radial arms on said huh, twin links pivotally and loosely connected with their inner ends to the free ends oi. said arms, a trunnion connecting the '1 no ends to said free links. said trunnion being provided with an excentric cylindrical. van a ment between the links, a triangular hanr nier head loosely mounted on said etrrentrie ei'ilargcinent and provided with a triangular bore having rounded corners, said rounded corners having approximately the same curvature as the cylindrical enlargement oi the trunnion. and the distance between the trunnion and the pivot being such that the hammer head is apable of performing complete revolutions at all times.

In testimony that I claim the foregoing as my invention, 1 have signed my name.

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